A novel WDM-PON architecture enabling multicasting with color-free ONUs based on WSS and interleaver

We propose a novel multicast-enable wavelength-division-multiplexed (WDM) passive-optical-network (PON) architecture that uses two sidebands of Optical Carrier Suppressed (OCS)-DPSK signal to carry the unicast and multicast data. The multicast wavelength control is realized through a Wavelength Selective Switch (WSS). At the optical line terminal (OLT), for each WDM channel, a single drive Mach-Zehnder modulator (MZM) is used to generate a subcarrier double-sideband (DSB) DPSK signal. Then, the lower-sideband signals are separated by an interleaver and subsequently modulated to deliver the multicast data, while the remaining upper-sideband DPSK signals carry the downstream unicast data. In the optical network units (ONUs), part of the downstream unicast signal power is re-modulated for upstream transmission, which enables color-free ONUs. This proposed scheme is experimentally demonstrated with a 1.25Gb/s downstream unicast and multicast data.